vs 

QUICK ANSWER
"Por qué" is a form of "por qué", a phrase which is often translated as "why". "Por qué no" is a form of "por qué no", a phrase which is often translated as "why not". Learn more about the difference between "por qué" and "por qué no" below.
por qué(
pohr
 
keh
)
A phrase is a group of words commonly used together (e.g., once upon a time).
phrase
a. why (adverb)
¿Por qué no te gustan las guayabas?Why don't you like guavas?
a. why (adverb)
Me gustaría saber por qué los gatos ronronean.I would like to know why cats purr.
a. what (pronoun)
¡Por qué cascadas más hermosas pasó la lancha!What beautiful waterfalls the skiff passed through!
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
masculine noun
a. reason
No tenían por qué sospechar que yo era un espía.They had no reason to suspect I was a spy.
Copyright © 2025 Dictionary Media Group, Inc.
por qué no(
pohr
 
keh
 
noh
)
A phrase is a group of words commonly used together (e.g., once upon a time).
phrase
a. why not
Por qué no bañarse de noche en el lago. A mí me parece una gran idea. - A mí también.Why not go for a swim at night in the lake at night. I think it's a great idea. - Me too.
b. why not?
¿Te apetece cenar conmigo esta noche? - Sí, por qué no.Do you feel like having dinner with me tonight? - Yes, why not?
a.
This refers to an idiomatic word or phrase for which there is no word-for-word translation.
no direct translation
No sé por qué no le pides a Claudio que te invite a cenar. Seguro que dice que sí.I don't know why you don't ask Claudio to take you to dinner. He'll surely say yes.
¿Por qué no quieres venir con nosotros, Lisa?Why don't you want to come with us, Lisa?
Copyright © 2025 Dictionary Media Group, Inc.